BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > Suspension | Brakes | Chassis
 
Post Reply
 
Thread Tools Search this Thread
      02-12-2012, 10:43 AM   #1
paradocs98
Major
United_States
29

 
paradocs98's Avatar
 
Drives: 2014 991 Carrera S
Join Date: May 2009
Location: NY


Posts: 1,347
iTrader: (0)

StopTech rotor wear allowances

Tried my best searching for this--extensive Google searches and an email to StopTech which was not answered:

What is the minimum rotor thickness for StopTech rotors? My ST60/ST40 BBK comes with 380x35mm front rotors and 355x32mm rear rotors. I'm on my third set of Street Performance pads in just under a year with the BBK setup, and I'm wondering when I need to consider replacing the rotors, or "friction rings" as StopTech calls them (thanks for pointing this out, Richard).

Richard at M-World did a recent DIY for replacing the friction ring component of the rotor assembly (rotor assembly consists of aluminum rotor hat secured to iron friction rings). I thought I may have seen somewhere that 2mm is the allowed wear for the rotor thickness before they should be replaced, but I can't find this reference. I believe Richard indicated he was replacing them after three pad changes.

It's not an insignificant concern because replacing the friction rings alone (and leaving the rotor hat as is) is upwards of $600 per axle. I realize it's a wear item, but I don't want to replace them prematurely and throw out good pieces.

Once I can get a digital caliper to measure my current rotor thickness, I'll have a better idea of how much wear the rotors have seen at this point. In my three pad set changes I've replaced all four pads at a time each time, but it was only the fronts that were seeing the majority of the wear. Each time the rear pads still had quite a bit of material left on them (there I go again, throwing out good pieces prematurely...). So I would assume that my rear rotors have not seen the wear that my fronts have, and so my strategy will probably be to just replace the front friction rings at this point.

I started thinking about this because track season is approaching and I'll likely try the Pagid RS29s now as an upgrade from the StopTech Street Performance pads.

Any thoughts or comments welcome.
Appreciate 0
      02-12-2012, 01:32 PM   #2
AMPowerJ
One mod leads to another ...
United_States
58

 
AMPowerJ's Avatar
 
Drives: 2015 F80 M3
Join Date: Apr 2008
Location: Blythewood, SC


Posts: 2,577
iTrader: (9)

In the same boat as you ... I believe it is 2mm worth of wear and then the friction rings should be replaced. I have been using ST pads but I am going to run RS29's at VIR in a couple weeks. I am going to measure mine but I doubt they are toast after just a few track days.
__________________

Current: 2015 F80 M3 (SS, Full Black Interior, 6MT, LED Lights, Adaptive Suspension, 19's)
Previous: 2013 E92 M3, 2013 F10 M5, 2009 E90 M3, 1998 E36 M3
Appreciate 0
      02-12-2012, 04:09 PM   #3
paradocs98
Major
United_States
29

 
paradocs98's Avatar
 
Drives: 2014 991 Carrera S
Join Date: May 2009
Location: NY


Posts: 1,347
iTrader: (0)

Quote:
Originally Posted by AMPowerJ View Post
In the same boat as you ... I believe it is 2mm worth of wear and then the friction rings should be replaced. I have been using ST pads but I am going to run RS29's at VIR in a couple weeks. I am going to measure mine but I doubt they are toast after just a few track days.
Excellent! Keep us posted.

Where did you source the Pagids?

Last edited by paradocs98; 02-12-2012 at 04:25 PM.
Appreciate 0
      02-12-2012, 09:51 PM   #4
Richard@M-World
United_States
25

 
Richard@M-World's Avatar
 
Drives: NASA TTA #92 M3
Join Date: May 2011
Location: TX/IL


Posts: 683
iTrader: (0)

Yes sir 2 mm on your rotors.

The min thickness allowance is typically listed on rotors (stock and aftermarket) as well, although they may become hard to read after a while due to rust. Let me know if you need any help with pads, rotors, etc.
__________________
Authorized AiM Dealer - Solo/Solo DL | SmartyCam HD | www.m-world.us
Appreciate 0
      02-13-2012, 01:52 AM   #5
aus
Major General
114

 
Drives: Odysse
Join Date: Jul 2005
Location: Seal Beach, CA


Posts: 7,375
iTrader: (5)

So how does one measure this 2mm thickness? Is it the metal on each side of the vent strip?
__________________
Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
Appreciate 0
      02-13-2012, 02:08 AM   #6
Richard@M-World
United_States
25

 
Richard@M-World's Avatar
 
Drives: NASA TTA #92 M3
Join Date: May 2011
Location: TX/IL


Posts: 683
iTrader: (0)

Yup. Found this on Google. Do note that sometimes a disc could wear unevenly, so be sure to measure the area which has the minimum thickness.

__________________
Authorized AiM Dealer - Solo/Solo DL | SmartyCam HD | www.m-world.us
Appreciate 0
      02-13-2012, 07:20 AM   #7
Bubbles
Brigadier General
Cayman Islands
85

 
Bubbles's Avatar
 
Drives: Green Bastard
Join Date: Jun 2007
Location: Bishop Bend


Posts: 3,554
iTrader: (3)

I was told the friction rings can be run pretty low, as long as you aren't having major crack or heat checking. Porsche guys run the rotors down to the slot levels in some cases. Of course, it's a safety preference at the end of the day and $600 isn't much if you consider what could happen if a rotor fails.
__________________
Appreciate 0
      02-13-2012, 07:36 AM   #8
quads
Lieutenant Colonel
27

 
Drives: bac mono
Join Date: Apr 2010
Location: racetrack


Posts: 1,643
iTrader: (3)

what is the thickness of the rings when new?
Appreciate 0
      02-13-2012, 08:56 AM   #9
M3SQRD
Colonel
United_States
24

 
M3SQRD's Avatar
 
Drives: E92 M3s, R56 Cooper S
Join Date: Jun 2009
Location: EC


Posts: 2,479
iTrader: (2)

Quote:
Originally Posted by 4sevens.com View Post
what is the thickness of the rings when new?
Quote:
Originally Posted by paradocs98 View Post
Tried my best searching for this--extensive Google searches and an email to StopTech which was not answered:

What is the minimum rotor thickness for StopTech rotors? My ST60/ST40 BBK comes with 380x35mm front rotors and 355x32mm rear rotors.
The 380 mm-dia ring is 35 mm-thick, and the 355 mm-dia ring is 32 mm-thick.
Appreciate 0
      02-13-2012, 09:28 AM   #10
quads
Lieutenant Colonel
27

 
Drives: bac mono
Join Date: Apr 2010
Location: racetrack


Posts: 1,643
iTrader: (3)

thanks dbarnes - I scanned the previous posts too quickly
Appreciate 0
      02-13-2012, 11:21 AM   #11
M3SQRD
Colonel
United_States
24

 
M3SQRD's Avatar
 
Drives: E92 M3s, R56 Cooper S
Join Date: Jun 2009
Location: EC


Posts: 2,479
iTrader: (2)

Quote:
Originally Posted by 4sevens.com View Post
thanks dbarnes - I scanned the previous posts too quickly
No problem - we've all done it at some point
Appreciate 0
      02-13-2012, 01:27 PM   #12
Richard@M-World
United_States
25

 
Richard@M-World's Avatar
 
Drives: NASA TTA #92 M3
Join Date: May 2011
Location: TX/IL


Posts: 683
iTrader: (0)

Some of the earlier kits for the E9X used 380x32 mm front. Just FYI. When in doubt, check embossed min thickness recommendation on your rotor
__________________
Authorized AiM Dealer - Solo/Solo DL | SmartyCam HD | www.m-world.us
Appreciate 0
      02-13-2012, 11:02 PM   #13
aus
Major General
114

 
Drives: Odysse
Join Date: Jul 2005
Location: Seal Beach, CA


Posts: 7,375
iTrader: (5)

So you replace after you wear down 2mm? So for the newer kits, 33mm?
__________________
Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
Appreciate 0
      02-13-2012, 11:20 PM   #14
Richard@M-World
United_States
25

 
Richard@M-World's Avatar
 
Drives: NASA TTA #92 M3
Join Date: May 2011
Location: TX/IL


Posts: 683
iTrader: (0)

^Yup
__________________
Authorized AiM Dealer - Solo/Solo DL | SmartyCam HD | www.m-world.us
Appreciate 0
      02-14-2012, 08:44 PM   #15
HP Autosport
United_States
406

 
Drives: F80 M3
Join Date: Mar 2007
Location: Santa Barbara, Brembo, GIAC, Koni, Ohlins, Performance Friction, Quaife, Stoptech, Vorshlag


Posts: 11,388
iTrader: (29)

Quote:
Originally Posted by paradocs98 View Post
Tried my best searching for this--extensive Google searches and an email to StopTech which was not answered:

What is the minimum rotor thickness for StopTech rotors? My ST60/ST40 BBK comes with 380x35mm front rotors and 355x32mm rear rotors. I'm on my third set of Street Performance pads in just under a year with the BBK setup, and I'm wondering when I need to consider replacing the rotors, or "friction rings" as StopTech calls them (thanks for pointing this out, Richard).

Richard at M-World did a recent DIY for replacing the friction ring component of the rotor assembly (rotor assembly consists of aluminum rotor hat secured to iron friction rings). I thought I may have seen somewhere that 2mm is the allowed wear for the rotor thickness before they should be replaced, but I can't find this reference. I believe Richard indicated he was replacing them after three pad changes.

It's not an insignificant concern because replacing the friction rings alone (and leaving the rotor hat as is) is upwards of $600 per axle. I realize it's a wear item, but I don't want to replace them prematurely and throw out good pieces.

Once I can get a digital caliper to measure my current rotor thickness, I'll have a better idea of how much wear the rotors have seen at this point. In my three pad set changes I've replaced all four pads at a time each time, but it was only the fronts that were seeing the majority of the wear. Each time the rear pads still had quite a bit of material left on them (there I go again, throwing out good pieces prematurely...). So I would assume that my rear rotors have not seen the wear that my fronts have, and so my strategy will probably be to just replace the front friction rings at this point.

I started thinking about this because track season is approaching and I'll likely try the Pagid RS29s now as an upgrade from the StopTech Street Performance pads.

Any thoughts or comments welcome.
On the 35mm rotor your minimum thickness is 33mm and on the 32mm rotor your minimum thickness is 30mm.
Appreciate 0
      02-15-2012, 08:07 AM   #16
Bubbles
Brigadier General
Cayman Islands
85

 
Bubbles's Avatar
 
Drives: Green Bastard
Join Date: Jun 2007
Location: Bishop Bend


Posts: 3,554
iTrader: (3)

Quote:
Originally Posted by Richard@M-World View Post
Some of the earlier kits for the E9X used 380x32 mm front. Just FYI. When in doubt, check embossed min thickness recommendation on your rotor

I just bought a used kit which could be an "earlier" kit, it's already on the car. Where is the min thickness designation on the rotor? Thank you in advance.
__________________
Appreciate 0
      02-15-2012, 10:57 AM   #17
Richard@M-World
United_States
25

 
Richard@M-World's Avatar
 
Drives: NASA TTA #92 M3
Join Date: May 2011
Location: TX/IL


Posts: 683
iTrader: (0)

On the outer edge of the rotor.
__________________
Authorized AiM Dealer - Solo/Solo DL | SmartyCam HD | www.m-world.us
Appreciate 0
      02-15-2012, 11:21 AM   #18
Bubbles
Brigadier General
Cayman Islands
85

 
Bubbles's Avatar
 
Drives: Green Bastard
Join Date: Jun 2007
Location: Bishop Bend


Posts: 3,554
iTrader: (3)

Quote:
Originally Posted by Richard@M-World View Post
On the outer edge of the rotor.
Great, thank you.
__________________
Appreciate 0
      02-15-2012, 07:23 PM   #19
paradocs98
Major
United_States
29

 
paradocs98's Avatar
 
Drives: 2014 991 Carrera S
Join Date: May 2009
Location: NY


Posts: 1,347
iTrader: (0)

Thanks for all the replies. I'll probably replace the front friction rings for now and keep an eye on the rears this season.
Appreciate 0
      02-29-2012, 12:47 AM   #20
paradocs98
Major
United_States
29

 
paradocs98's Avatar
 
Drives: 2014 991 Carrera S
Join Date: May 2009
Location: NY


Posts: 1,347
iTrader: (0)

Followup to original post--I got a high-quality digital caliper and measured my rotors the other day. After two sets of the Street Performance pads and 8-10 track days, the wear is less than I would have expected. Front rotors are around 34.3mm (35mm new) and rears are around 31.7mm (32mm new). So I'll keep these rotors for now and measure thickness periodically this season with the new Pagid pads. I called StopTech and they confirmed that this is fine.
Appreciate 0
      02-29-2012, 01:07 AM   #21
HP Autosport
United_States
406

 
Drives: F80 M3
Join Date: Mar 2007
Location: Santa Barbara, Brembo, GIAC, Koni, Ohlins, Performance Friction, Quaife, Stoptech, Vorshlag


Posts: 11,388
iTrader: (29)

Quote:
Originally Posted by paradocs98 View Post
Followup to original post--I got a high-quality digital caliper and measured my rotors the other day. After two sets of the Street Performance pads and 8-10 track days, the wear is less than I would have expected. Front rotors are around 34.3mm (35mm new) and rears are around 31.7mm (32mm new). So I'll keep these rotors for now and measure thickness periodically this season with the new Pagid pads. I called StopTech and they confirmed that this is fine.
You are well above the min. specs so you are ok.
Appreciate 0
      02-29-2012, 07:18 AM   #22
akh23456
All I do is Win... Eat Race Sleep
United_States
33

 
akh23456's Avatar
 
Drives: F10 M5
Join Date: Mar 2009
Location: Philly


Posts: 2,119
iTrader: (2)

Garage List
2009 M3  [4.28]
2013 f10 M5  [0.00]
great info guys i can't wait for my stop Tech to go on.
__________________

F10 M5: 11.308 131.96 with a 1.9 60ft Street Tires
E90 M3: 11.2 126.7 with a 1.8 60ft Street Tires
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 11:19 AM.




m3post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST